Just wondering: As an alternative to a big block HF, could we also do a HF which mines 12 blcoks/hr and halves the reward?

I don't assume I'm the first one to think of this. So why doesn't this seem to be an option? An obvious advantage would be that confirmations would be faster. So I must be missing a big disadvantage...

Ten minutes was specifically chosen by Satoshi as a tradeoff between first confirmation time and the amount of work wasted due to chain splits. After a block is mined, it takes time for other miners to find out about it, and until then they are actually competing against the new block instead of adding to it. If someone mines another new block based on the old block chain, the network can only accept one of the two, and all the work that went into the other block gets wasted. For example, if it takes miners 1 minute on average to learn about new blocks, and new blocks come every 10 minutes, then the overall network is wasting about 10% of its work. Lengthening the time between blocks reduces this waste.

More of the hash power is wasted when using shorter block times, which can decrease the security. It can also result in re-org taking significantly longer after a fork occurs. There's also the fact that the shorter block time which could be practical (say 2.5 to 5 minutes) isn't actually short enough for what you're talking about anyway (which is most likely going into a shop and expecting it to be confirmed on the spot).

Increasing the speed of blocks is also a more complicated change and requires changing more variables, so it could leave room for error.

There is an advantage that I can think of - that miners can have less variance when mining on smaller pools, which in turn can reduce the risk of a "mining cartel" - but I don't think that it's worth it.

Shorter block time will lead to Orphan Block and i think it's worse than the idea of raising block size a lot. Also, it could complicate things such as halving reward in future and miner with slow internet connection/response time might at disadvantage.

Apart from all the concerns raised, faster blocks would result in a centralization risk. The more blocks you propogate, the larger the blockchain becomes. Miners will access to huge storage, can only run a full node. 10minute block times helps to slow such centralization risk.

GeoPin : Blockchain-based interface to the physical world (http://www.geopin.network/)

Internet speeds have increased, storage costs have gone down, hash power has increased dramatically, all this has happened since Bitcoin started. Halving the block generation time, and reducing block size would still leave us ahead based on the improved efficiency. The other big change is the centralisation of mining, and my gut feeling is that faster blocks could re-introduce more miners. I don't have enough knowledge to justify this.

Massive amounts of hash power are wasted all the time. I don't see how faster block generation and speeding up transaction confirmations will affect this. other than making the system more efficient.

During 2013..2015, the times different scaling proposals were analyzed, I proposed reducing the block time to 1 minute. I did some research that ended with the DECOR+ PoW consensus algorithm as an alternative to Nakamoto Consensus.

The DECOR+ protocol is what powers the RSK Bitcoin Sidechain (check rsk.co).

There has been a lot more research about this since 2014. My current understanding is that shorter block intervals down to 1 minute for Bitcoin are ok because block propagation has improved (however the blocks would need to be 1/10th of the current size). For even shorter intervals, more cooperative consensus protocols are required to prevent the generation of stale blocks to be a significant disadvantage.

Just wondering: As an alternative to a big block HF, could we also do a HF which mines 12 blcoks/hr and halves the reward?

I don't assume I'm the first one to think of this. So why doesn't this seem to be an option? An obvious advantage would be that confirmations would be faster. So I must be missing a big disadvantage...

A block of a given size takes a given amount of time to traverse the network so everyone can get started mining it. With 1 mb blocks it takes 12s. This means that the shorter the blocktime the bigger percentage of "head start" nearby miners get than farther away miners. You can shrink the block size or increase the blocktime to even the playing field between everyone on the network.

FYI to get it so that everyone has a 99% even playing field for every block you need to have 12KB max blocksize and 7 min blocktime. So ya bitcoin actually isn't slow enough to be fair.